This invention relates generally to electrotherapy and more particularly concerns electrodes for low intensity direct current generators.
In recent years, low intensity, direct current therapy (LIDC) has become a medically accepted method for the treatment of skin ulcers, surface wounds and the like. It has been found that the proper application of LIDC yields a beneficial factor for skin trauma and accelerates the healing process of various skin lesions by stimulating tissue growth.
The open lesions and ulcers to be treated by LIDC are often infected with pathogens such as bacteria. As to be discussed later in fuller detail, your applicant has succeeded in combining the features of LIDC therapy with the known antiseptic properties of silver and silver salts by using the low intensity direct current to affect ion transfer of germicidal silver ions to the lesion or ulcer in a manner not to be confused with iontophoresis.
For LIDC therapy, direct current of the proper magnitude is directed through the lesion by means of electrodes mounted upon the skin in proximity to the lesions. An example of apparatus providing a constant level of direct current to electrodes is disclosed in a copending application by Anton Horn, Electrotherapy Device, U.S. Pat. No. 3,918,459. Electrodes containing particulate silver or carbon in a non-porous elastomer structure have been used for LIDC therapy. These electrodes are typically applied to the patient's skin by means of adhesive tape while interposed between the electrodes and the skin are several layers of gauze saturated with conductive electrolyte such as Ringer's solution to lower the interface resistance. Such electrodes perform no function other than to conduct the current from the LIDC generator to the body.
Iontophoresis apparatus is old in the electrical therapeutic art. U.S. Pat. No. 3,289,671, Iontophoresis method by E. T. Trotman et al. filed Sept. 11, 1963, describes an apparatus providing a constant current source for practicing iontophoresis. Iontophoresis is usually carried out by applying positive and negative electrodes to opposite side of a body member such as the forearm. One electrode rests on an absorbent pad which is applied to the skin and saturated with a liquid drug susceptible to ionization so that when electric current is applied to the electrodes ions of the drug molecules pass from one electrode into the skin towards the other electrode. The drug is usually dissolved in a fluid which normally is comprised of a solvent and the ionic medicament to be applied. The solvent used for iontophoresis is substantially non-conductive so that the medicament constitutes substantially the only current in the electrolyte fluid. Simple aqueous solutions have most commonly been used for the electrolyte.
Iontophoresis treatment requires currents of the magnitude of 2 milliamps whereas the current found benefical for germicidal LIDC therapy is in the order of 10 microamps.
Electrodes containing a mixture of silver and silver salts, such a silver chloride are known in the electro-cardiograph art. U.S. Pat. No. 3,574,305, Detection of Electrophysicological Potentials or of Currents by Gerhard Muhl, and U.S. Pat. No. 3,834,373, Silver, Silver Chloride Electrodes by Takuya R. Sato, are two of many examples of silver silver chloride electrodes intended for the use in the field of cardiology for measurement of electrocardiograms. These electrodes are to be separated from the skin by means of conductive gel which effectively prevents silver migration to the wound, preventing the germicidal effect of silver ions.